research digest
Creating a Risk Model for Glaucoma
A group of physicians has proposed a patient-management tool, similar to one used in cardiology.

A group of physicians recently reported a new approach for assessing glaucoma risk factors that could someday help ophthalmologists decide when to initiate treatment. The group published its theory in the September issue of the American Journal of Ophthalmology (AJO).

The idea of developing a glaucoma risk model was due in part to the landmark Framingham Heart Study. This study initially involved 5,209 adult residents of Framingham, Mass., and examined the development and progression of heart disease. The study has published numerous findings on predictive risk factors for heart disease.

One of the authors of the AJO article discussed the connection of heart disease and glaucoma with Ophthalmology Management. "Through this study [Framingham], cardiology has refined its model of risk. In ocular hypertension and glaucoma we see some parallels," says Robert Fechtner, M.D., professor of ophthalmology at the New Jersey Medical School, University of Medicine and Dentistry of New Jersey (UMDNJ). The difference, he notes, is that studies have already identified glaucoma risk factors.

Established Research

One of the previous studies the group looked at in developing their theory was the Ocular Hypertension Treatment Study (OHTS), which identified at least four prominent risk factors for developing glaucoma: increasing age, higher IOP, larger vertical cup disc diameter, and thinner central cornea thickness. Dr. Fechtner is hopeful that by taking these factors and developing risk-assessment scenarios, OHTS researchers will create a risk calculator for doctors to assess patients with ocular hypertension and decipher what their chances are of being visually disabled. This will help determine when they should be treated.

Risk-Model Challenges

However, there are challenges to developing a risk calculator. Changes in the optic nerve and the retina can be undetectable and asymptomatic with tests. Also, there is no agreement in the field on criteria for the diagnosis of early damage that precedes vision loss on standard achromatic perimetry, leaving many to question how to assess actual risk.

"If you have a one in 100 chance of being visually disabled in your lifetime based on things we know about you today, before you have damage, should we be treating you today?" asks Dr. Fechtner.

Furthermore, differences between heart disease and glaucoma make it difficult for physicians to parallel the Framingham study. Whereas cardiologists can work with patients to modify several risk factors, such as smoking or high cholesterol, ophthalmologists can only modify intraocular pressure.

However, William Kannel, M.D., senior investigator and director of the Visiting Scientist Program at the Framingham Heart Study, co-author of the AJO article, believes a risk-assessment calculator has to start somewhere and be built upon with new research. "These are always works in progress, and you do the best you can with what you have," explains Dr. Kannel. "Then, you test it out with populations. You apply the risk algorithms to a particular population under surveillance and see how well it performs."

Back to School

In the interim, Dr. Fechtner is leading a continuing medical education initiative on the topic. He's the course director of "Treatment of Risk in the Glaucoma Continuum," which is sponsored by the UMDNJ Medical School Institute of Ophthalmology and Visual Science, the UMDNJ Center for Continuing and Outreach Education, and Medical Intervention Systems.

Dr. Fechtner is optimistic about treatment. "I imagine a future in which I'm going to have a risk calculator in the examination room that may even include actuarial tables. With patients sitting in front of me, I'll be able to come up with a pretty good estimate of their risk of being visually disabled over the next 10 to 15 years."